doc: Dictionaries are ordered since Meson 0.62.0

This is a side effect of requiring Python >= 3.7 which itself guarantees
dictionary order. This is now a Meson language guarantee as well which
is required for passing default_options as dict and is generally
expected by users.

docs/yaml/elementary/dict.yml

@@ -8,8 +8,9 @@ description: |
   You can also iterate over dictionaries with the [`foreach`
   statement](Syntax.md#foreach-statements).
 
-  *(since 0.48.0)* Dictionaries can be added (e.g. `d1 = d2 + d3` and `d1 += d2`).
+  *(since 0.48.0)*: Dictionaries can be added (e.g. `d1 = d2 + d3` and `d1 += d2`).
   Values from the second dictionary overrides values from the first.
+  *(since 0.62.0)*: Dictionary order is guaranteed to be insertion order.
 
 
 methods: